1. Field of the Invention
This invention relates to a system and method for the production of gypsum in a plant. More particularly, the present invention relates to recovering heat at various locations within a board manufacturing plant and using the recovered heat to reduce the energy needed for subsequent calcination.
2. Description of the Background Art
It is known in the art to calcine gypsum in the manufacture of plasters, stuccos, gypsum wallboards and other building materials. However, the plants that produce gypsum-based building materials tend to be extremely inefficient users of energy as large amounts of energy are needed to adequately dry gypsum. For instance, some processes require 60 lbs. of water to be evaporated for every 100 lbs of gypsum produced. The background art contains numerous examples of attempts to increase the efficiency of gypsum manufacturing methods.
Some of these systems recover the heat from calcination and use it for further calcination. For example, U.S. Pat. No. 2,934,830 to Zvejnieks discloses a method whereby hot water vapors obtained by calcinating gypsum are used to further calcinate and dry the gypsum. To achieve this, the apparatus includes a drying shaft that transports dried gypsum upwardly for removal at an upper outlet. Hot water vapors from a calcination apparatus are directed and delivered downwardly through the shaft as the gypsum is concurrently delivered upwardly. The hot water vapors are used to both heat and dry the gypsum within the shaft.
Furthermore, U.S. Pat. No. 1,798,857 to Tyler discloses a method for the continuous calcination of gypsum. The method employs steam obtained from gypsum that is calcined in kettles to heat a steam jacket and chamber. The steam provided to jacket serves to calcinate gypsum within chamber. Additional hot gases collected within a separator can also be reused.
Lastly, U.S. Pat. No. 1,746,294 to Tyler discloses a method for the continuous calcination of gypsum. The method employs a separating chamber that includes a steam dome and a condenser, whereby excess steam can be collected, condensed and stored for subsequent use. The apparatus further includes a pre-heater wherein gypsum is partially calcined. Heated steam from the partial calcination is collected and used for further calcination within an additional calcinating chamber.
Although the above referenced inventions achieve their respective objectives, none address the inefficiencies unique to the manufacture of alpha-type gypsum, nor do they address the inefficiencies inherent in the manufacture of gypsum based building materials, such as gypsum board. The present invention is directed to overcoming these inefficiencies.